This invention is in the field of target detecting sensors, and more particularly in the area of target detection in presence of clutter.
The prior art which was used to reject stationary clutter was the automatic clutter mapper. This automatic clutter mapper, which has been implemented in radar systems, gave good clutter rejection performance for stationary clutter which was consistently detected in a given automatic clutter mapper segment. Clutter was detected by incrementing an up-down counter by four with a detection, by one with a miss, until a sufficiently large number of detections had been counted that the probability was very low that they could have occurred due to a moving target. At the time clutter was indicated, the clutter amplitude was measured and a threshold was set to reject the clutter. Although this device worked well for rejecting clutter in a normal radar propagation environment, it allowed more than the allowable clutter false alarm rate in a severe ducting environment because with ducting the clutter did not occur consistently in the same automatic clutter mapper segment. Ducting is the condition when radar propagation is not straight line but trapped by unusual atmospheric conditions.